RE would not start - not even a splutter. I found that the 4 Iridium plugs ( only done 2,000km) would not give a spark at all. Changed plugs for the old ones I still had and first try running great.
Can anyone shed any light on why this would happen?
I can’t believe all 4 would fail at once??
I found out the hard way some years ago that the market is flooded with fake plugs, after questioning some iridium ones, not only do the fakes fail, but also snap off so you have the threads of a plug stuck in your head…
It’s an old bike and should run OK on the old style plugs. They have been trying these different new plugs for 40 years or more and I have probably tried them all. Eventually I have gone back to the original plugs because they work just as well and end up being a lot cheaper in the long run. If you use the recommended plugs in a popular well known brand then you can’t go wrong. Must agree that it is rather unusual that all four plugs would fail all at the same time.
Hey Stuart, you must have a lot of headaches with all those plugs stuck in your head. 
Sorry mate couldn’t resist. 
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I have a VF1000R that I changed to iridium plugs at the last service and the bike ran well once warm but wouldn’t start easily from cold in cold weather with choke, each time it was due fouled plugs…I changed back to standard NGK plugs and no issues!
Thanks for the reply Fry.
It appears that Iridium plugs are more prone to misfire when fouled.
I had run my bike with choke on for a few kms and plugs then failed to spark on later restart. On taking the plugs out for good clean I found a carbon build up. Once cleaned plugs fired again.
Seems carbon buildup shorts these plugs easily if you have short rides and rich mixture.
Is it possible that the Iridium plugs are colder plugs? Maybe try a hotter set of plugs because it sounds just like what happens when you use too cold a plug riding for short and slower distances they tend to foul up rather too quickly. When I have used hotter plugs around town, I found they kept cleaner and worked for longer. I realise different conditions in UK to here in AUS, but maybe worth someone trying it out in UK just to find out. Me personally, I just stick to the standard NGK plugs now. (well I did over 7 years ago when I was taken out bad enough to stop me riding but am working on a return). and older means slower these days. 
Cheers all
John
To return to this topic after some time I recently could not get a cylinder to fire from cold with an iridium plug. Changed to a normal NGK plug and cylinder fired right up. I have had various starting and running issues on iridium plugs since I got them. Thought it was a blocked idle jet at first. I am running the iridium plugs one grade hotter than the normal plugs to avoid fouling which seems to affect them.
NGK could not give a definitive reply as to whether a resistor in the plug lead and the resistor plug might be too much resistance. I could try removing the plug lead resistor and see if that helps but I think I will just stick to regular plugs.
Any member ever tested current draw of iridium plugs and whether old coils might not be up to the task?
Iridium is not the best conductor and its a trade off with the wear factor .
I would run the new NGK Ruthenium plugs as they are a better conductor than Iridium plugs and as such would not foul as easily .
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